J.S.S. Academy of Technical Education Department of Electronics and Communication Bangalore - 560060

BIONIC EYE

SEMINAR REPORT 2009 Submitted by: TEJAS (1JS03EC046)

Head of the department Prof. V.Aravamudhan Dept of E&C J.S.S.A.T.E

Principal Dr. A.N.N.Murthy

Bachelor of Engineering Visveshwaraya Technological University, Belgaum Evaluated by: 1. 2.

CERTIFICATEThis is to Certify that the seminar entitled BIONIC EYE is a bonafide work carried out by TEJAS, bearing the USN 1JS03EC046 in partial fulfillment for the award of degree of Bachelor of Engineering in Electronics and Communication of Visveshwaraya Technological University, Belgaum, during the academic year 2009. The seminar has been approved as it satisfies the requirement with respect to seminar work prescribed for 8th semester of Engineering Degree.

Head of the Department: Prof. V.ARAVAMUDHAN Professor and HOD Department of E&C JSSATE

Faculty in charge: Mrs.VEERAMMA YATNALLI Assistant Professor Department of E&C JSSATE

ACKNOWLEDGEMENTSNo work is complete without due recognition being given to people who made it possible. I would like to convey my profound gratitude for all those who have helped me in presenting this seminar paper. Firstly, I would like to thank Mrs. VEERAMMA YATNALLI, ASST.PROFESSOR, JSSATE, for her able guidance. With her help and suggestion, the presentation of this seminar paper has been rendered easier for me. I am grateful to Prof. V.ARAVAMUDHAN, our HOD for his timely support and encouragement towards the presentation of this seminar paper. I also express my deep sense of gratitude to all the Faculty Members of Electronics and Communication Department for their valuable guidance. I express my sincere thanks to my family and friends who also helped me to present this seminar article successfully.

TEJAS[1JS03EC046]

INDEXSl. No Topic Page No

1.

Introduction Function of the human eye Components of the bionic eye Operation of the bionic eye Case studies Current technologies

2.3. 4.

5. 6.

INTRODUCTIONVisual prostheticA visual prosthetic or bionic eye is a form of neural prostheses intended to restore lost vision or amplify existing vision. It usually takes the form of an externally-worn camera that is attached to a stimulator on the retina or optic nerve in order to augment or replace the real eye.

HistoryScientific research since at least the 1950s has investigated interfacing electronics at the level of the retina, optic nerve, thalamus, and cortex. Visual prosthetics do not yet offer the functionality of a real eye.

Biological considerationsThe ability to give sight to a blind person via a bionic eye depends on the circumstances surrounding the loss of sight. Candidates for visual prosthetic implants find the procedure most successful if the optic nerve was developed prior to the onset of blindness. Persons born with blindness may lack a fully developed optical nerve, which typically develops prior to birth. According to the Society for the Prevention of Blindness, between 10,000 and 12,000 people per year lose an eye. Though 50% or more of these eye losses are caused by an accident (in one survey more males lost their eyes to accidents compared to females), there are a number of inherited conditions that can cause eye loss or require a visual prosthetic. Microphthalmia is a birth defect where for some unknown reason the eye does not develop to its normal size. These eyes are totally blind, or at best might have some light perception.

Technological considerationsVisual prosthetics are being developed as a potentially valuable aide for individuals with visual degradation. The visual prosthetic in humans remains experimental, while visual prosthetics have been implemented in other animals. Visual prosthetics providing a level of visual acuity comparable to that of a camera are currently undergoing research trials in rats. Bionic visual implants have demonstrated the ability to partially recover lost sight in rats during laboratory testing. Structure/Function of the human eye

The eye An eye is a round-shaped organ that works with the brain to provide us with vision. The shape of the eye is maintained by the pressure of the aqueous humor. The aqueous humor is the fluid that fills the front chamber of the eye. At the back of every healthy human eye are millions of rods and cones - 120 million rods and around six million cones. They act as biological solar cells in the retina that convert light into electrical impulses, which then travel along the optic nerve to the brain where images are formed. If these cells degenerate or malfunction, the result is a loss of eyesight. The main function of the eye is to work with the brain to provide us with vision. The eye and brain translate light waves into a sensation we call vision.

Eye PartsThe eye has many parts. Some of the main parts are listed and described below.

lens The transparent crystalline lens of the eye is located immediately behind the iris. corneao

o

The cornea is a transparent dome which serves as the outer window of the eye. The cornea is the most powerful structure focusing light entering the eye. The retina is the innermost layer of the eye. It is composed of nerve tissue which senses the light entering the eye. The retina sends impulses through the optic nerve back to the brain, which translates the impulses into images that we see. There are 4 types of light-sensitive receptors found in the retina 1. rods 2. cones that absorb long-wavelength light (red) 3. cones that absorb middle-wavelength light (green) 4. cones that absorb short-wavelength light (blue) The pupil is the hole in the center of the eye where light passes through.

retinao o o

pupilo

iris The iris is the colored part of the eye. It is a thin diaphragm composed mostly of connective tissue and smooth muscle fibers. The iris lies between the cornea and the crystalline lens. optic nerve o The optic nerve is a continuation of the axons of the ganglion cells in the retina. It acts acts like a cable connecting the eye with the brain. o The optic nerve is also called the cranial nerve II. sclera o The sclera is the white, opaque portion of the eye. It provides protection and serves as an attachment for the extraocular muscles which move the eye.o

Diseases of the Eye That Can Potentially Be Cured

There are some diseases in which the sensors in the eye, the rods and cones, have deteriorated but all the wiring is still in place, says Ignatiev ,if we

could replace those damaged rods and cones with artificial ones, then a person who is retinally blind might be able to regain some of their sight. The artificial implants being developed at SVEC are intended to help people with retinal diseases such as macular degeneration and retinitis pigmentosa. Macular degeneration is an age-related disease and usually affects people over 50 years of age. According to Moorfields Eye Hospital in London, UK, it accounts for almost 50% of all visual impairment in the developed world. Retinitis pigmentosa causes the rods and cones in the eyes to malfunction, and tends to be hereditary. In the UK more than 25,000 families have RP, and globally this figure runs into millions, according to the British Retinitis Pigmentosa Society.

COMPONENTS OF THE BIONIC EYE

Digital

camera - built into a pair of glasses; captures images in realmicrochip - built into a handheld unit; processes

time; sends images to microchip Video-processing

images into electrical pulses representing patterns of light and dark; sends pulses to radio transmitter in glasses

lens -The transparent crystalline lens of the eye is located immediately behind the iris

Radio

transmitter - wirelessly transmits pulses to receiver implanted receiver - receiver sends pulses to the retinal implant by a hair-

above the ear or under the eye Radio

thin, implanted wire

Retinal

implant - array of 60 electrodes on a chip measuring 1 mm by

1 mm OPERATION OF THE BIONIC EYE

How does a "bionic eye" allow blind people to see?An incision is made in the white portion of the eye and the retina is elevated by injecting fluid underneath," explains Garcia, comparing the space to a blister forming on the skin after a burn. "Within that little blister, we place the artificial retina." These first-generation ceramic thin film microdetectors, each about 30 microns in size, are attached to a polymer carrier, which helps surgeons handle them. The background image shows human cones 5-10 microns in size in a hexagonal array. Image courtesy A. Ignatiev.

Scientists will unfamiliar

aren't yet certain how the brain interpret voltages from the artificial rods

and cones. They believe the brain will eventually adapt, although a slow

learning process might be necessary -- something akin to the way an infant learns shapes and colors for the first time.

The entire system runs on a battery pack that is housed with the video processing unit. When the camera captures an image -- of, say, a tree -- the image is in the form of light and dark pixels. It sends this image to the video processor, which converts the tree-shaped pattern of pixels into a series of electrical pulses that represent "light" and "dark." The processor sends these pulses to a radio transmitter on the glasses, which then transmits the pulses in radio form to a receiver implanted underneath the subject's skin. The receiver is directly connected via a wire to the electrode array implanted at the back of the eye, and it sends the pulses down the wire. When the pulses reach the retinal implant, they excite the electrode array. The array acts as the artificial equivalent of the retina's photoreceptors. The electrodes are stimulated in accordance with the encoded pattern of light and dark that represents the tree, as the retina's photoreceptors would be if they were working (except that the pattern wouldn't be digitally encoded). The electrical signals generated by the stimulated electrodes then travel as neural signals to the visual center of the brain by way of the normal pathways used by healthy eyes -- the optic nerves. In macular degeneration and retinitis pigmentosa, the optical neural pathways aren't damaged. The brain, in turn, interprets these signals as a tree, and tells the subject, "You're seeing a tree." All of this takes some training for subjects to actually see a tree. At first, they see mostly light and dark spots. But after a while, they learn to interpret what the brain is showing them, and eventually perceive that pattern of light

and dark as a tree. The first version of the system had 16 electrodes on the implant and is still in clinical trials at the University of California in Los Angeles. Doctors implanted the retinal chip in six subjects, all of whom regained some degree of sight. They are now able to perceive shapes (such as the shaded outline of a tree) and detect movement to varying degrees. The newest version of the system should offer greater image resolution because it has far more electrodes. If the upcoming clinical trials, in which doctors will implant the second-generation device into 75 subjects, are successful, the retinal prosthesis could be commercially available by 2010. The estimated cost is $30,000.

Real-time visionThe user wears a pair of glasses that contain a miniature camera and that wirelessly transmits video to a cellphone-sized computer in the wearer's pocket. This computer processes the image information and wirelessly transmits it to a tiny electronic receiver implanted in the wearer's head. When received in the implanted chip, the digital information is transformed into electrical impulses sent into the ganglion cells. From there, the brain takes over as the information travels down the optic nerve to the visual cortex at the back of the brain. The whole process occurs extremely rapidly, so that patients see in real-time. This is important any noticeable lag could stimulate the "vestibular-ocular reflex", making people feel dizzy and sick.

1: Camera on glasses views image 2: Signals are sent to hand-held device 3: Processed information is sent back to glasses and wirelessly transmitted to receiver under surface of eye 4: Receiver sends information to electrodes in retinal implant 5: Electrodes stimulate retina to send information to brain Humayun's team is about to embark on a new trial of an improved device, which they will fit into 50 to 75 people aged over 50, who are also blind as a result of retinitis pigmentosa. The trial will involve monitoring them for two years and will take place in five centres across the US.

Field of viewThe first implant had just 16 electrodes on the retinal pad and, as a result, visual information was limited. The new device has 60 electrodes and the receiver is shrunk to one-quarter of the original's size. It is now small enough to be inserted into the eye socket itself. The operation to fit the implant will also last just 1.5 hours, down from 7.5 hours. Currently recipients of the device experience a relatively narrow view, but

more electrodes should provide a greater field of vision, Humayun says. By stimulating more ganglion cells, he hopes that visual acuity will increase dramatically. His team's next goal is to design a device with 1000 electrodes. Regaining sight has felt like a miracle to those involved in the preliminary trial. At the beginning, it was like seeing assembled dots - "now it's much more than that," says Terry Bryant, aged 58, who received the implant in 2002 after 13 years of blindness. "I can go into any room and see the light coming in through the window. When I am walking along the street I can avoid low hanging branches and I can cross a busy street." If the trial is successful, the new device may be available commercially by 2009, priced around $30,000 - similar to a cochlear implant, Humayun says. People whose blindness results from a range of causes, including retinitis pigmentos and macular degeneration could benefit from it.

'Bionic eye' may help reverse blindnessA "bionic eye" may one day help blind people see again, according to US researchers who have successfully tested the system in rats. The eye implant - a 3-millimetre-wide chip that would fit behind the retina could be a dramatic step above currently available technology, says the team at Stanford University, California, US. About 1.5 million people worldwide have a disease called retinitis pigmentosa, and 700,000 people in the western world are diagnosed with age-related macular degeneration each year. In both degenerative diseases,

retinal cells at the back of the eye that process light gradually die. Groups at the University of Southern California and the University of Illinois at Chicago Medical Center, both in the US, have developed retinal implants for humans to improve these conditions. But Daniel Palanker, a physicist at Stanford working on the bionic eye, says these implants have very low resolution. Basically, [that work is] a proof of principle, Palanker says. He claims his system has higher resolution. A visual acuity of 20/20 is considered normal, while 20/400 is considered blind. Palanker and his team say their device could provide acuity of 20/80. With 20/80 vision you can certainly read large forms and live independently, Palanker says. Its a huge step forward.

Wireless transmissionFor the device to work, the microchip would have to be implanted behind the retina of the blind person. The patient would wear goggles mounted with a small video camera. Light enters the camera, which then sends the image to a wireless wallet-sized computer for processing. The computer transmits this information to an infrared LED screen on the goggles. The goggles reflect an infrared image into the eye and on to the retinal chip, stimulating photodiodes on the chip. The photodiodes mimic the retinal cells by converting light into electrical signals, which are then transmitted by cells

in the inner retina via nerve pulses to the brain. The goggles are transparent so if the user still has some vision, they can match that with the new information - the device would cover about 10 of the wearers field of vision. CASE STUDIES

Living-cell movement STUDIES CONDUCTED ON ANIMALSIn the rat study, Palanker showed that by placing the implant behind the retina, the remaining living retinal cells moved closer to the photodiodes on the implant The closer the cells get to the array, the better the resolution of the image. Palanker says that his goal is for there to be no more than 10 microns of space between the retinal cells and the implant, equivalent to the width of just one cell. When the implants were used in blind rats, the rodents appeared to have some restored vision. Rats with the retinal implants passed a vision test by responding to having a pattern of black and white stripes waved in front of them. Before the device can be stepped up to humans, Palanker says the team will have to trial larger implants in bigger animals and conduct more safety tests. CASE STUDIES ON HUMANS

A Canadian farmer and father of eight, Jens lost his sight 18 years ago in an accident. Now he's able to navigate through rooms, find doors and even drive a car to some degree.

"I was able to very carefully drive and look from myleft side to my right side, making sure I was between this row of trees on the right and the building on my left," he says. "When I got near any obstruction, I would see that there was an obstruction. I would also see the lack of obstructions, knowing I wasn't going to run over anybody ... It was a very nice feeling." The black and white image Jens sees is not solid, but resembles a dot matrix pattern. It's like looking at a sport scoreboard with different light patterns illuminated to show different scores. The miniaturization of equipment and more powerful computers have made this artificial vision possible, but it's not cheap: The operation, equipment and necessary training cost $70,000 per patient.

Although the images produced by the artificial eye were far from perfect,

they could be clear enough to allow someone who is otherwise blind to recognise faces, he said. The breakthrough is likely to benefit patients with the most common cause of blindness, macular degeneration, which affects 500,000 people in the UK. This occurs when there is damage to the macula, which is in the central part of the retina where light is focussed and changed into nerve signals in the middle of the brain. The implant bypasses the diseased cells in the retina and stimulates the remaining viable cells. See the light Professor Dagnelie said: "The retinal implant contains tiny electrodes. If you stimulate a single electrode, the person will see a single dot of light." They have already tested implants containing a handful of electrodes, but the end device will contain 50-100 to give a better overall picture. "We are hoping this will be enough for the person to be able to make their way through a building, find a door or window and avoid obstacles for example. "To us, the images look very basic but for someone who was previously blind they are a massive step forward." But he added: "There is still quite a bit of work that will be needed to fine tune it. Being able to see faces will be quite a bit down the line."

He said training the individual to learn how to interpret the blurry images should help. Anita Lifestone of the RNIB, said: "This is a revolutionary piece of technology and really has the potential to change people's lives. But we need to be aware it is still some way in the future." Since Swedish engineer Arne Larsson received the first fully implanted cardiac pacemaker more than 40 years ago, researchers around the world have looked at ways of improving peoples lives with artificial, bionic devices. One of the most dramatic applications of bionics is the creation of artificial eyes. Early efforts used silicon-based photodetectors, but silicon is toxic to the human body and reacts unfavourably with fluids in the eye. Now, scientists at the Space Vacuum Epitaxy Centre (SVEC) based at the University of Houston, Texas, are using a new material they have developed, tiny ceramic photocells that could detect incoming light and so repair malfunctioning human eyes.

Success of Silicon Microdetectors to DateSilicon has not been successful to date, and its use continues to suffer from problems of deterioration of the chip, contamination of the eye and atrophy of the retina, says Alex Ignatiev, a Professor at the University of Houston and Director of SVEC. Our ceramic microdetectors should overcome all of these problems. In fact, SVECs thin, photosensitive ceramic films respond to light as much as rods and cones do.

CURRENT TECHNOLOGIES

Microsystem-based Visual Prosthesis (MIVIP)Designed by Claude Veraart at the University of Louvain, this is a spiral cuff electrode around the optic nerve at the back of the eye. It is connected to a stimulator implanted in a small depression in the skull. The stimulator receives signals from an externally-worn camera, which are translated into electrical signals that stimulate the optic nerve directly.[2]

Implantable Miniature TelescopeAn Implantable Miniature Telescope is one type of visual prosthetic that has met with some success in the treatment of end-stage age-related macular degeneration. This type of device is implanted in the eye's posterior chamber and works by increasing (by about three times) the size of the image projected onto the retina in order to overcome a centrally-located scotoma or blind spot. Success has also been achieved with retinal implants which use an array of electrodes connected to an external camera.

Harvard/MIT Retinal ImplantJoseph Rizzo and John Wyatt at MIT and the Massachusetts Eye and Ear Infirmary have developed a stimulator chip that sits on the retina and is in turn stimulated by signals beamed from a camera mounted on a pair of glasses. The stimulator chip decodes the picture information beamed from the camera and stimulates retinal ganglion cells accordingly.

The Dobelle EyeSimilar in function to the Harvard/MIT device, except the stimulator chip sits in the primary visual cortex, rather than on the retina. One subject has had the system implanted in his brain since 1978 with no ill effects.

The Virtual Retinal Display (VRD)Laser-based system for projecting an image directly onto the retina. This could be useful for enhancing normal vision or bypassing an occlusion such as a cataract, or a damaged cornea.

Other projectsOther notable researchers include Richard Normann and David Bradley at University of Chicago, Ed Tehovnik at MIT, a California-based company named Second Sight and Mark Humayun at the University of Southern California. Clinical trials have recently been announced for a retinal implant developed in the US. Presently these technologies are only able to transmit a 10x10 pixel image as shown in the image below,but this is expected to improve with time.

FUTURE OF THE BIONIC EYE Artificial Retina (ASR Silicon)

The brothers Alan Chow and Vincent Chow have developed a microchip containing 3500 solar cells, which detect light and convert it into electrical impulses, which stimulate healthy retinal ganglion cells. The ASR requires no externally-worn devices. Today,restoring sight to the blind might seem like a myth or a science fiction,but researchers are making significant progress and the reality of a bionic eye being extensively used commonly to cure blindness may not be a far fetched idea. References1. James Geary (2002). The Body Electric. Pheonix.

2. Chun DW, Heier JS, Raizman MB. (2005). "Visual prosthetic device

for bilateral end-stage macular degeneration.". Expert Rev Med Devices. 2 (6): 657-65.3. Lane SS, Kuppermann BD, Fine IH, Hamill MB, Gordon JF, Chuck

RS, Hoffman RS, Packer M, Koch DD. (2004). "A prospective multicenter clinical trial to evaluate the safety and effectiveness of the implantable miniature telescope.". Am J Ophthalmol. 137 (6): 9931001.4. Lane SS, Kuppermann BD. (2006). "The Implantable Miniature

Telescope for macular degeneration.". Curr Opin Ophthalmol. 17 (1): 94-8.5.

Jonathan Fildes. "Trials for bionic eye implants", BBC, 16 February 2007. Sources

"Bionic eye will let the blind see." BBC News. Apr. 5, 2005. http://news.bbc.co.uk/2/hi/health/4411591.stm

Fildes, Jonathan. "Trials for 'bionic' eye implants." BBC News. Feb. 16, 2007. http://news.bbc.co.uk/2/hi/science/nature/6368089.stm Fleming, Nic. "Bionic eye that restores sight to the blind." Telegraph. Feb. 18, 2007. http://www.telegraph.co.uk/news/main.jhtml?xml=/news/ 2007/02/17/nsight17.xml Second Sight http://www.2-sight.com/index.html

"Second Sight Medical Retinal Prosthesis Receives FDA Approval for Clinical Trials." medGadget. Jan. 10, 2007. http://www.medgadget.com/archives/2007/01/second_sight_me.html US Air Force and VISX Corp, a company based in California, US.

Journal of Neural Engineering (DOI: 10.1088/1741-2560/2/1/012)